Esterquat, a quaternary ammonium compound, is a fabric softening molecule. It is typically formed when the reaction product of long chain (C12-C22 or C16-C18) fatty acids and a tertiary amine is esterified in the presence of an acid catalyst and subsequently quaternized to obtain quaternary ammonium salts. The final product is a mixture of mono, di and tri ester components. The quaternary ammonium compound giving particular good performance and stability profiles are obtained from reaction of C12-C22 fatty acids or the hydrogenation products, usually containing some degree of unsaturation, the iodine value range of 20-90.
Saturated alkyl chains deliver greater softening efficacy compared to unsaturated ones. Cationic surfactants, when dispersed in water, form multilayer particles called vesicles that in turn deposit on fabrics. Saturated alkyl chains deliver stronger vesicle structure giving higher softening efficacy as well as fragrance delivery, compared to unsaturated alkyl chains. The increment in saturation level, however, increases the melting point and imposes handling and processing challenges because of the higher melting material. Currently, esterquat products contain 75% soft and 25% hard fatty acids or 100% hard fatty acids.